java 7 - How to change tomcat compiler

Question

I'm trying to use the new Java 7 switch on strings feature.

But Tomcat is not cooperating.

I've made sure that tomcat is running under java 7 but it seems that it's not compiling under it.

I've added the following to the web.xml file, under the jsp servlet entry

    <init-param>
        <param-name>compiler</param-name>
        <param-value>C:/Program Files/Java/jdk1.7.0/bin/javac.exe</param-value>
    </init-param>

but it doesn't seem to do the trick.

Any tips would be appreciated.

Answer 1

We are running Tomcat 6 and had the same problem. Our solution was to:

• replace tomcat/lib/ecj-3.3.1.jar with ecj-3.7.2.jar (can be taken from the latest Tomcat 7 release);

• add this to tomcat/conf/web.xml

  ...
  <servlet>
    <servlet-name>jsp</servlet-name>
    <servlet-class>org.apache.jasper.servlet.JspServlet</servlet-class>
    <init-param>
        <param-name>fork</param-name>
        <param-value>false</param-value>
    </init-param>
    <init-param>
        <param-name>xpoweredBy</param-name>
        <param-value>false</param-value>
    </init-param>
    <init-param>                                    <!-- this should be added -->
        <param-name>compilerSourceVM</param-name>
        <param-value>1.7</param-value>
    </init-param>
    <init-param>
        <param-name>compilerTargetVM</param-name>
        <param-value>1.7</param-value>
    </init-param>                                   <!-- last added line -->
    <load-on-startup>3</load-on-startup>
  </servlet>
  

The simpler alternative is, of course, to install Tomcat 7 but this might not be an option for everyone.